Who doesn’t look better in profile?: water levels, methods of regulation, and the St. Lawrence River and Lake Ontario

The levels of the St. Lawrence River and Lake Ontario are both regulated by various dams and other works built as part of the St. Lawrence Seaway and Power Project as well as methods outlined by the International Joint Commission (IJC). Over the last few years, there has been ongoing study and public consultation about revising the method of regulation (i.e. the high and low water levels of the water), including the recent announcement to adopt Plan Bv7, I thought I would provide the following post. As part of my forthcoming book on the history of the St. Lawrence Seaway and Power Project, I have researched and written about the evolution of the method of regulation, and the following is an excerpted and somewhat modified version of what currently appears in the book manuscript:


During the construction phase of the Seaway and Power Project a “river profile” – the engineering method of regulating the river and its water levels, as well as those of Lake Ontario – had to be established. The explicit goal was to maintain the water levels at an average that equated to “natural levels” but also to improve on nature by removing the extremes of high and low and flows. “Natural” was defined as that which had existed before the Gut dam was installed in the St. Lawrence in the early 20th century.[1] Yet establishing exactly what constituted a “state of nature” was problematic from the outset, not only because representatives of the two countries disagreed upon the historic impact of the Gut dam, but because it was difficult to find information regarding the natural levels to use as a baseline. The Joint Board of Engineers had set the elevation of 248.1 (feet above sea level) as the high water level in 1926, but there was concern that the geological phenomenon of earth tilt had made this measurement unreliable. Indeed, engineering studies indicated that natural factors played a much larger role in raising water levels than had the man-made factors (i.e. diversions into the Great Lakes basin).

Nonetheless, 248 feet was taken as the extreme elevation since a minimum and maximum range of levels needed to be determined so that the various governmental and construction entities would know the depth to which they needed to dig channel and locks, as the cost to the power entities for dredging would rise several million dollars for each foot the water levels were lowered.[2] By the early 1950s it was apparent to engineers that the existing Method of Regulation No. 5 was only an interim measure until a Board of Control was created to better ascertain the means of controlling the water profile. The 1952 order of approval had also provided that any interests (e.g. shore-front property) would be given adequate legal protection and indemnity in their respective country. Largely in response to the complaints of the Lake Ontario Land Owners and Beach Protection Association, which represented shore owners, the Lake Ontario levels issue was given its own docket in addition to the St. Lawrence project. The Lake Ontario Joint Board of Engineers was formed in 1953, and the Lake Ontario issue became intertwined with the St. Lawrence discussions, as any decision about levels on the river would affect the lake. The corollary of restricting Lake Ontario water levels was the various downstream impacts; for example, lowering water levels by a foot meant the annual loss of 225,000,000 kilowatt hours of power development at the Barnhart dam.

On 1 March 1954, the Canadian and American sections of the Joint Board of Engineers had reached agreement on administrative and operating procedures, and received the first plans for approval in July 1954. As the binational negotiations for a joint vs. solely Canadian seaway reached their pinnacle in 1954, the International Joint Commission (IJC) engineers were busy utilizing models to simulate historical water levels on the St. Lawrence River and Lake Ontario. It became apparent that there had been errors in the calculation of Method of Regulation No. 5, as it would barely lower the maximum levels on Lake Ontario.[3] R.A.C. Henry, one of the Canadian experts on the engineering aspects of the St. Lawrence, commented on the process whereby the engineering representatives of the two countries had established the previous “238-242” levels for Barnhart dam: “In light of the evidence which is available on the subject it appears reasonably certain that the 238-242 range was actually a compromise between two conflicting views and was not based upon any positive and well-defined line of reasoning … .”[4]

Yet Henry and his colleagues were not immune from similar errors. Between 1954 and 1959 there were many engineering errors, miscalculations, assumptions, guesses, and partisan positions. Shortly after Henry’s observation, in an internal Canadian meeting, HEPCO General Manager Otto Holden stated outright that they did not know what the natural conditions were. General McNaughton, who reputedly dominated the IJC and was known as a tough Canadian nationalist, emphasized “that the balance of conditions on Lake Ontario is so delicate that he could not feel assurance that the engineers could in fact keep the levels within the 244-248 range.”[5] As a result, they strove to attain levels “as nearly as may be.” However, in public they gave an impression of preciseness and confidence.

To be fair, the planners were in many ways products of their training and societal ideals, and were subject to dominant national and transnational ideas that promoted the collaboration of industrial capital and the state as necessary to maximize the development of natural resources in the name of economic and social progress. They believed they were wisely maximizing natural resources. There was great societal and occupational pressure on the “experts” to provide answers and do so in a confident manner: in addition to hundreds of millions of dollars, many jobs and related economic factors, national and organizational pride, and the role of technology and expertise in capitalist/democratic and communist Cold War tensions, their personal and professional stature was at stake.

The Canadian and American sections of the International Lake Ontario Board of Engineers disagreed about the maximum level of Lake Ontario. The U.S. thought it should be 248 feet, the Canadians advocated for 248.3, with a minimum of 243. A month later, the U.S. side pushed for a range of 243-247. The Americans seemed to be largely motivated by political concerns stemming from the protests of Lake Ontario beach owners, while the Canadian position was largely predicated on protecting Montreal interests, for any lowering of Lake Ontario levels would tend to raise water levels in the western Quebec section of the St. Lawrence.[6] The main users of the Seaway and Power Project – power production, navigation, shoreline property, and downstream interests – wanted different minimum and maximum water levels or varying ranges of stages (i.e. difference between high and low levels) and pleasing everyone seemed impossible. At the various public hearings that were conducted on the lake levels, many people came to voice their concern about the impact of higher water levels, such as shoreline erosion. However, the transcripts show that property owners were worried about their own property value, rather than nature or ecological impact.

Nevertheless, in March 1955 the International Joint Commission told the Canadian and American governments that it was possible to regulate the St. Lawrence and Lake Ontario in such a way as to protect the power, navigation, and riparian interests.A revised method of regulation was arrived at, labeled 12-A-9, but there were problems with that as well: for example, tests showed that under its parameters the seaway would constrict the channel at Montreal. There was discussion about increasing the upper limit marginally from 248.0 to, for example, 248.3, but such precise goals appear, in retrospect, somewhat strange given the uncertainty about the evidence and tests they used – engineers were trying to ascertain the historic conditions on which they based their arguments at the same time they were making their arguments – and the idea of 248 “as nearly as may be” continued to prevail. In July 1956 the IJC issued a supplementary order directing that Lake Ontario levels be maintained between 244 and 248, as nearly as may be. Yet soon after, method 12-A-9 was replaced by another method, 1958-A.

Plan 1958-A remained as the provisional working model throughout the construction phase (1954-1959) of the St. Lawrence Seaway and Power Project, although engineers were clear that it would likely need to be adjusted, and it was superseded by Plan 1958-C at the beginning of 1962, which in turn was replaced the following October by 1958-D. In the longer term, compared to pre-project conditions, the St. Lawrence and Lake Ontario water levels were more predicable and controllable, and the range of water levels were compressed (i.e. extreme highs lower, extreme lows higher). But the method of regulation was not always satisfactory, as there were significant problems with low water levels in the river in the 1960s, and then high water levels in the 1970s (method of regulation 1958-DD, which incorporates 1958-D, was eventually developed to deal with fluctuation conditions). These were attributed to natural supplies of greater variance than had occurred in the 100-year period upon which the engineers had based the various methods of regulation.[7] Additionally, over time it became apparent that steady water levels were detrimental to the St. Lawrence ecosystem, which benefits from natural variability. In 2012, the IJC announced a new method of regulation, Bv7, that allows for more natural fluctuation cycles.


[1] IJC, Canadian Section, docket 67-2-5:6: Lake Ontario Levels Reference, Meetings, McNaughton, Burbridge, Cote 1953/01/16, Memorandum to General McNaughton re August 29, 1952 meeting, September 2, 1952.

[2] Government of Canada, Library and Archives Canada (LAC), RG 25, vol. 6352, file 1268-AD-40, pt 1, St. Lawrence Project: Dredging at Cornwall Island (Dec 1, 1954 to March 25, 1955), Memorandum for the Minister – St. Lawrence Project, January 24, 1955.

[3] The long term average flow (1860-1954) was determined to be 240,000 cfs, which was about 4000 cfs more than the average used for Method of Regulation No. 5 IJC, Canadian Section, docket 68-5-1: St. Lawrence Project, Miscellaneous Memoranda, March 1954 – Memorandum. Studies showed that the impact of the levels of Gut Dam had been exaggerated and was really about 4 ½ inches, which was approximately half of what had been believed by some. IJC, Canadian Section, 68-2-5:6-1: St. Lawrence Power Application, Minutes of IJC Meetings. 1952/07 & 1962/04, St. Lawrence Power Application: modification of Order of Approval (Executive Session, Boston), April 9, 1954.

[4] IJC, Canadian Section, 68-3-V2: St. Lawrence Power Application, Correspondence From 1954/01/01 to 1954/12/21, Henry to McNaughton, Re: 238-242 Controlled Single Stage Project, International Rapids Section, May 12, 1954.

[5] IJC, Canadian Section, 68-3-V2: St. Lawrence Power Application, Correspondence From 1954/01/01 to 1954/12/21, Memorandum of Meeting, July 3, 1954.

[6] The regulation criteria outlined that the water level of Montreal Harbour would be no lower than would have occurred if the power project had not been built. Bryce, 94; LAC, RG 25, vol. 6778, file 1268-D-40, pt 43.2, St. Lawrence Seaway and Power Project – General File, DEA Memorandum: Lake Ontario levels, April 26, 1955.

[7] Bryce, 108.

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